Cancer Diagnosis

Cancer diagnosis

Can be divided into laboratory diagnosis and clinical features of the neoplasm or by it is clinically important effects into
 
Local clinical features
Distant clinical features
Systemic features of the tumour

 Laboratory diagnosis

The definitive diagnosis of solid tumors is usually obtained with a biopsy of the lesion


 Biopsy determines the tumor histology and grade and thus assists in definitive therapeutic planning

When a biopsy has been obtained at an outside institution, the slides should be reviewed to confirm the outside diagnosis

Biopsies of mucosal lesions usually are obtained endoscopically e.g., via colonoscope. bronchoscope, or cystoscope

Lesions that are easily palpable, such as those of the skin, can either be excised or sampled by punch biopsy

 Deep-seated lesions can be localized

with CT scan or ultrasound guidance for biopsy

A sample of a lesion can be obtained with

•  Fine-needle aspiration
•    Open incisional biopsy
•  core-needle biopsy

•  excisional biopsy

  

 Fine-needle aspiration is easy and relatively safe, but has
the disadvantage of not giving information on tissue architecture

. For example, fine-needle aspiration biopsy of a breast mass can make the diagnosis of malignancy, but cannot differentiate between an invasive and non invasive tumor

  Core-needle biopsy is more advantageous when the histology will affect the recommended therapy

Core biopsy like fine-needle as­ piration, is relatively safe and  can be performed either by direct palpation (e.g a breast mass or a soft-tissue mass) or can be guided by an imaging stady (e.g., stereotactic core biopsy of the breast

 Core biopsies, like fine-needle aspirations, have the disadvantage of introducing sampling error

For example, some patients with a diagnosis of atypical ductal hyperplasia on core biopsy of a mam­mographic abnormality are found to have carcinoma upon excision of the lesion it is crucial to ensure that the histologic findings are
consistent with the clinical scenario, and to know the appropriate interpretation of each histologic finding

 
, Open biopsies have the advantage of providing more tissue for
histologic evaluation and the disadvantage of being an operative procedure

lncisional biopsies are reserved for very large lesions in which a definitive diagnosis cannot be made with needle biopsy

 Ex­cisional biopsies are performed for lesions in which core biopsy is either not possible or is non diagnostic

Excisional biopsies should be performed with curative intent, that is, by obtaining adequate tissue around the lesion to ensure negative surgical margins

 Orien­tation of the margins by sutures or clips by the surgeon and inking of the specimen margins by the pathologist will allow for determi­nation of the surgical margins and will guide surgical re-excision

If one or more of the margins are positive for microscopic tumor or close

The biopsy incision should be oriented to allow for excision­ of the biopsy scar if repeat operation is necessary

The biopsy incision should directly overlie the area to be removed rather than tunneling from another site, which runs the risk of con­taminating a larger field

Finally, meticulous hemostasis during a biopsy is essential since a hematoma can lead to contamination of the tissue planes and can make subsequent follow-up with physical examinations much more challenging

What are the techniques of tumours cytology 

These including the following cytology techniques

Bruchings eg oesophagus and cervix

FNAC , Fluids either physiological eg cells in urine or sputum or pathological eg cells in ascites or pleural effusion

 The cytological features of malignancy are

• loss of cellular cohesiveness: nuclei oriented in different directions and are irregularly­
  spaced
• Cells become detached from one another
•   Pleomorphism: variation in size, shape and number of nucleoli
•  moulding of nuclei: nuclei appear pushed into one another or stacked together like a vertebral column
•  Nuclear to cytoplasmic ratio increased
•  Chromatin shows irregular clumping and hyperchromasia nuclear membrane is irregular with angular bites
• Abnormal mitoses may be present

 
what are the difference between cytology and histology in the diagnosis of malignancy

• Fine nuclear detail may be lost in formalin fixed histology

•  Cohesiveness of cells is more easily evaluated on cytologic material
• Histologic sections provide added information on tissue architecture and relation­ ship of cancer cells to normal structures depth of invasion, presence of vascular invasion, etc 

What are the histological features or architectural of malignant tumours they are 

invasion of the underlying or surrounding tissue: extension of tumour beyond the basement membrane for carcinomas and an irregular front penetrating the surrounding tissue
for mesenchymal tumour

stromal changes: the change that occurs in the stroma as tumour invades is called desmoplasia it is a response to invasion of tissue by malignant tumour cells

Loss of normal structure: as tumours become less and less differentiated, they resemble the tissue of origin less and less­

new structures: some tumours will create structures such as glandular structures colon, endometrium cancers or papillary structures thyroid, bladder cancers

Necrosis: may indicate areas of tumour that have insufficient blood supply Angiogenesis and neovasculature

 Inflammation: tumours often cause inflammation and the inflammatory infiltrate is visible immunostaining: an antibody is raised against a protein of particular prognostic significance­
the distribution and concentration of which can then be identified
It can be used for
 
• Identifying poorly differentiated tumours

• Sub-typing tumours

• Identifying an unknown primary from a metastatic deposit

• Assessing tumour microvessel density and angiogenesis


tags:cancer,diagnosis